Radial tire with additional sidewall reinforcement

ABSTRACT

A radial tire is formed with the usual radial carcass and, in each sidewall, an additional reinforcement ply comprising cords arranged circumferentially of the tire and having a stiffness which generally increases with increasing distance from the axis of the tire from a minimum value at the edge adjacent to the bead wire to a maximum value at the other edge. In manufacturing the tire on a building drum, the cords selected to form the additional ply comprise a fragile core portion and a portion wound in a helix around the core and capable of elongation by rupture of the core and increase of the pitch of the helix. During the subsequent shaping, the cords of the additional ply automatically acquire the proper stiffness. This produces a tire providing improved road qualities and passenger comfort.

United States Patent [191 Boileau [451 Sept. 9, 1975 RADIAL TIRE WITH ADDITIONAL SIDEWALL REINFORCEMENT [75] Inventor: Jacques Boileau, Clermont-Ferrand,

France 22 Filed: Nov. 14, 1973 211 Appl. No.2 415,684

Related US. Application Data [62] Division of Ser. No. 326,115, Jan. 23, 1973, Pat. No.

[56] References Cited UNITED STATES PATENTS 3 O44,522 7/1962 Drakeford Ct a1... 152/362 R 3,044,523 7/1962 Drakeford Ct 211... 152/362 R 3,253,636 5/1966 Travers 152/362 R 3.422.874 1/1969 WeiQcl l 156/128 1 3,455,100 7/1969 Sidles ct a1. 156/128 1 3,500,890 3/1970 Boileau 152/354 3,557,860 1/1971 Maiocchi 152/362 R 3,722,567 3/1973 Delobelle... 152/354 R 3,756,883 9/1973 Gay l 156/128 1 3,765,468 10/1973 Verdier 152/354 R 3,776,293 12/1973 Marzocchi 156/128 1 Primary Examiner-Clifton B. Cosby Attorney, Agent, or FirmBrumbaugh, Graves, Donohue & Raymond [57] ABSTRACT A radial tire is formed with the usual radial carcass and, in each sidewall, an additional reinforcement ply comprising cords arranged circumferentially of the tire and having a stiffness which generally increases with increasing distance from the axis of the tire from a minimum value at the edge adjacent to the bead wire to a maximum value at the other edge. In manufacturing the tire on a building drum, the cords selected to form the additional ply comprise a fragile core portion and a portion wound in a helix around the core and capable of elongation by rupture of the core and increase of the pitch of the helix. During the subsequent shaping, the cords of the additional ply automatically acquire the proper stiffness. This produces a tire providing improved road qualities and passenger comfort.

2 Claims, 6 Drawing Figures RADIAL TIRE WITH ADDITIONAL siiiEw LL REINFORCEMENT This is a divisional of 'U.S." application/Seh'No. 326,115, filed Jan. 23, 1973, now U.S. Pat No. 3,800,844. Y

BACKGROUND OF THE I VENTION 1 This invention relates to tires and, more particularly,

to novel and highly-effective tires of the r'adiahcarcasstion. These characteristics are due in large measure to plies of cords of preferably rigid material which are oriv ented substantially circumfere nt iall y'. On the other hand, the sidewalls are made flexible the use of cords which are arranged in radial planes of the tire' and therefore do not intersect. This construction facilitates radial deformation of the sidewalls. i i

This basic scheme, as originally devised, lisubjected tocertain corrections, since the' flexi the sidewalls has certain disadvantages. In particular, it may give rise to instability at high speed, a flut t e' ring of the rim with respect to the tread, and an excessively long time of response to the actions of the steering wheel. The corrections made to overcome thesedra wbacks have consisted in reinforcing the sidewalls, in particular between the midheight of the sidewall and the bead. Various solutions have been proposed. These solutions all have various drawbacks. Without speaking of the difficulties in manufacture whichthey entail,

SUMMARY OF THE INVENTION An object of the present invention is to remedy the problems of radial tires outlined above and, in particular, to provide a radial tire characterized by both a high degree of passenger comfort and superior road qualities. Another objectof the invention is to provide a method of making the new tire,.

The foregoing and otherobjects are attained in accordance with the invention by the provision of. a radial-carcass tire having, in each sidewall, in addition to the usual carcasscordsror cables,,an vadditionalreinforcement extending between the beadwiresand the middle of the sidewall or beyond. .The additional rein-, forcement comprises cords or cables arranged circumferent'ially and having a stiffness that increases, generally as a function of the distance from the axis of the tire. from a minimum value at the edge adjacentto thebead wires to a maximum value at the otheriedgeu- The stiffness' of a cord or cable is definedas the ratio F/AL/L, in which F is a tensile force applied to the cord or cable and AL/L is the resulting relutiveelongw tion of the cord or cable.

. v 2 stiffnesses of the cords or cables'at different distances from the bead wires must be compared for one and the same force Fand'under the very conditions in whicht hey find themselvesin the sidewall 'of the tire. In practiceyone can, forinsfance'; cut from the sidewall of the tire circumferential strips having the 'samewidth, for instance 1 cm, and each containing a number of cords;-subject each strip to a force nF, n being the number of cords in the strip and F being'identical for all ."strips; and measure the elongation L for a length L of with the invention has practically as much effectiveness with respect to the road qualitiespf thetire as a rein-- forcem ent of maximum; uniform stiffnessdOn the other hand, the variation in stiffness has a very favorable effect on' passenger comfort, since it increases the radial flexibilityiand filters and .darnps the shock waves transmitted from the tread to the'rirn.

In order to produce a tire which has a reinforcement of stiffness which increases asa function of the distance from th e' axis in its sidewall, one proceeds as follows in accordance with the invention: Upon the building of the tirefth e carcass or plies-are wound in a conventional manner on a buildingdrurn and the bead wires position. Before the edges of the carcass ply or plies arebent around the" bead wires, the reinforcement pl yi or plies are pu tinpla'ce, their cords being inclined 30 atan' angle'betw ee n 0 5 to the circumferential directionf There is.preferably 'used a ply in'which the cords extend at an angle of 0 i e., in the circumferenti al direction The ply is wound until overlap of its ends after having made one, andpr eferably several, turns: In order to permit the shaping of the carcass thus produc edgthle cords of the ply are wound helieallyaround va fragile central core. During the shaping, the core breaks andthe pitchof the helix increases gradually as a function of the elongation imposed until, for the fadi ally outermost cord, all undulation disappears.

The tire' is preferably characterized by a number of additional features:

a. The cords of the additional reinforcement are I made of polyamide or another elastic material.

b. The cords are calendered in a rubber of a modulus of elasticity greater than or equal to 250 g/mm at 100% elongation.

, I c. Between the carcass ply or plies on the one hand and the additional sidewall reinforcements on the other 50 hand, there is interposed a layer of rubber the minimum thickness of which is at least equal to the diameter of the largest cords used in; the carcass and reinforcement-plies; This intermediate-rubber has a modulus,of elasticity lessthan that ofthecalendering rubber of the sidewallreinforcementcords.

, d;. Ihe additional sidewall reinforcement.,egttendi at least over three-quarters of thdheight of theitire between-the bead wires and-.the midpoint-of the sidewall, that is to say,.thepoint-of the sidewallfarthest fromthe median plane-and preferably overat leas't all this height; 3. i i; BRiE pEsfcRiPTioN oF'r'H DRAWING "ALbetterunderstanding of the invention can be.

'- gained from a consideration of the following detailed description of the preferred embodiments thereof, in conjunctionwithgtheapp ended figures of the drawing,

wherein: l l 1 3 FIG. 1 is a view in radial section of a tire according to the invention; 1

FIG. 2 is a view in elevation, partly broken away, of a sector of the sidewall of the same tire, the cords being shown farther apart than actually is the case for the 5 sake of greater clarity;

FIG. 3 is a view in radial section, on a larger scale. of a portion of the reinforcement of one of the sidewalls, showing the portion divided intostrips of equal width;

FIG. 4 is a view in radial section of a carcass during the building thereof on a building drum;

FIG. 5 is a view in elevation of areinforcement cord employed in the. additional sidewall reinforcement in accordance with the invention; and

FIG. 6 is a very schematic end elevation of the cords L of the additional plies in accordance with the invention arranged on a building drum.

DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1' shows a tire 1 comprising a'tread 2 andsidewalls 3. The reinforcement of the tire comprises a carcass ply 6 the ends 7 and 8 of which are wound around bead wires 9. As FIG. I and 2 show, the cords of the carcass ply 6 are arranged radially.

The tire reinforcement further comprises two tread plies l and I l of steel cords between the carcass 6 and the tread 2. The reinforcement comprises also two plies l4 and 15 of cords in each sidewall 3 between each of the bead wires 9 and a point I2 located past the middle 13 of the sidewall. As shown in FIG. 2, the cords of the layers I4 and I are arranged parallel to the circumferential direction. Near the bead wires at I6 they have a slightly undulating appearance. On the other hand. on

4 l. Carcass (plies) Materialz. polyamide Denier of the cords: 1880 X 3 Spacing: 0.85 mm Angle with respect to the circumferential direction:

90 Modulus of the calendering rubber: 390 g/mm at 10071 elongation 2. Tread Reinforcement (plies 10 and 11) Material: steel Type of cords: four strands of 0.23 mm; hoop of O. l 2

Spacing: 0.85 mm Angles with respect to the circumferential direction:

,+24 and -,24 3. Reinforcement of the sidewalls (plies l4 and 15) Material: polyamide Denier of the cords: 940 X 3 Core: polyvinyl-alcohol staple-fiber yarn measuring 16.934 km for 500 g of yarn Twist of the cord 27 around the core 26: 300

turns/meter Elongation without tension after rupture of the core:

19% to 26% Spacing: 1.6 mm Angle with respect to the circumferential direction:

0 Modulus of the calendering rubber: 390 g/mm at v 100% elongation Width: 7 cm 4. lnterposed rubber (layer 18 of rubber) Modulus: 325 g/mm at l00% elongation FIG. 3 shows how the plies l4 and 15 taken from a tire have been cut into strips A, B, C, D, E, F, G, each the other edge of the ply at l2 they are stretched. 35 of a width of I cm, in order to measure their elastic The plies l4 and 15 are inserted, near the bead wires, properties. between the carcass 6 and its folded-back portions 7 The following table gives the results of these meaand 8, and they are separated from the carcass 6 by a surements:

Strip Flon- I-Ilon- Elon- Rup- Stiff- Stiff- Stiffgation gation gation ture ness ness ness at under under upon force at 3 at 7 rupture 3 daN 7.daN rupture (daN) daN -daN (daN) .4 '2; 7r (daN (daN A 10.15 22.11 40.2 111.72 29.6I 30.7 46.6 1; (1.15 20.25 39.00 19.40 48.8 34.55 49.7 C 7.05 10.5 32.55 111.90 42.5 42.4 58.1 1) 7.20 13.95 30.15 19.24 41.7 50.2 63.8 E 3.90 1 1.10 26.70 20.04 77 63.l 75.0 F 3.30 8.55 22.35 21.514 91 8L9 96.6 (i 3.00 7.05 17.70 18.24 100 91 5 103 relatively thick layer of rubber 18. As can be seen, the sidewall reinforcement has a stiff- FIG. 4 shows on the building drum the carcass 6, ness which is two to three times greater in the region G. the bead wires 9, the' folded-back carcass portions 7 which is most distant from the bead wires, than in the 55 and 8, and the additional reinforcement plies l4 and 15, the cords of which are'perpendicular to those of the carcass 6. I

FIG. 5 shows a cord of the type used for making the plies l4 and 15. This cord 25 comprises a core 26 of small diameter serving as support for the cord proper region A, which is closest to the bead wires. This heterogeneity is remarkable and confers great advantages, namely excellent comfort, in particular silent travel, excellent stability of the sidewalls, and direct and soft response to the movements of the steering wheel.

Many modifications of the preferred embodiments of the invention disclosed herein will readily occur to those skilled in the art upon consideration of this disclosure. Accordingly, the invention is to be construed as including all embodiments thereof within the scope of the appended claims.

I claim:

l. A method of manufacturing a radial-carcass tire, comprising the steps of laying bead wires and a carcass 5 of cords on a cylindrical building drum. placing on the portions of the carcass intended to lie in the region of each sidewall of the tire extending from one of said bead wires to a point at least three-quarters of the way to the midpoint of the sidewall at least one ply of additional cords oriented perpendicularly to the cords of said carcass, said additional cords comprising a fragile core portion and a portion wound in a helix around the core and being capable of elongation by rupture of the core and increase of the pitch of the helix, and expand- 6 ing the carcass to shape the tire, elongate the additional cords, break the core portions, and increase the pitch of the portions wound in a helix as a function of the elongation imposed.

2. A method according to claim 1 wherein each ply of additional cords is wound around the drum a plurality of times and wherein the ends of each ply overlap a short distance.

UNITED STATES PATENT AND TRADEMARK OFFICE CERTIFICATE 0F CORRECTION e PATENT NO. 3,904

DATED September 9, 1975 INV ENTOR(S) I JACQUES BOI'LEAU It is certified that error appears in the above-identified patent and that said Letters Patent are hereby corrected as shown below:

First Page, Item February 3, 1972 should be inserted.

Signed and ficaled this Third Day Of August 1976- [30] Foreign Application Priority Data France Q .72.037l8" {SEAL} Attest:

RUTH C. MASON C. MARSHALL DANN 4118511718 ff Commissioner ofParents and Trademarks 

1. A METHOD OF MANUFACTURING A RADIAL-CARCASS TIRE, COMPRISING THE STEPS OF LAYING BEAD WIRES AND A CARCASS OF CORDS ON A CYLINDRICAL BUILDING DRUM, PLACING ON THE PORTIONS OF THE CARCASS INTENDED TO LIE IN THE REGION OF EACH SIDEWALL OF THE TIRE EXTENDING FROM ONE OF SAID BEAD WIRES TO A POINT AT LEAST THREE-QUARTERS OF THE WAY TO THE MIDPOINT OF THE SIDEWALL AT LEAST ONE PLY OF ADDITIONAL CORDS ORIENTED PERPENDICULARLY TO THE CORDS OF SAID CARCASS, SAID ADDITIONAL CORDS COMPRISING A FRAGILE CORE PORTION AND A PORTION WOUND IN A HELIX AROUND THE CORE AND BEING CAPABLE OF ELONGATION BY RUPTURE OF THE CORE AND INCREASE OF THE PITCH OF THE HELIX, AND EXPANDING THE CARCASS TO SHAPE THE TIRE, ELONGATE THE ADDITIONAL CORDS, BREAK THE CORE PORTIONS, AND INCREASE THE PITCH OF THE PORTIONS WOUND IN A HELIX AS A FUNCTION OF THE ELONGATION IMPOSED.
 2. A method according to claim 1 wherein each ply of additional cords is wound around the drum a plurality of times and wherein the ends of each ply overlap a short distance. 